This invention relates to a method and an apparatus for manufacturing laminate for honeycomb structures and more particularly it relates to a method and an apparatus capable of easily and continuously manufacturing laminate for honeycomb structures comprising precisely formed cells and having excellent functional features such as a good air permeability.
1. Prior Art
Conventional methods and apparatuses for manufacturing laminate for honeycomb structures are generally classified into two types, those of a first type that involve steps of applying an adhesive agent to a material strip being unwound from a roll, drying it, cutting the strip to sheets of a unit length and bonding them together to form laminate for honeycomb structure and those of a second type that form a strip of laminate for honeycomb structure simply by bonding a number of component strips and winding it up onto a roll.
Additionally, there are methods and apparatuses of a third type, or a modified first type, where the applied adhesive may or may not be dried before the rolled material strip is cut to sheets of a unit length to form a laminate for honeycomb structure.
Technologies for the above described first, second and third groups are disclosed in Japanese Patent Laid-Open Nos. 224825/88, 157847/85 and 255422/85 and Japanese Patent Publication 30184/81 respectively.
In any of the above conventional methods and apparatuses, an emulsion type adhesive agent containing water or a solvent other than water as a diluent or a hot-melt type agent containing synthetic resin that becomes adhesive when heated and/or pressurized is normally employed.
The method and apparatus according to said Japanese Patent Laid-Open No. 224825/88, which belong to the first type, require complicated mechanical and electric means for establishing and maintaining a given ratio of the rate of revolution of a roll of a strip-shaped material to which an adhesive agent being applied to that of another roll of the material which is being cut in order to produce sheets of the material of a given unit length and, additionally, steps for drying the applied adhesive agent.
The complicacy of this technique makes the overall process of manufacturing laminate for honeycomb structure rather inefficient.
Japanese Patent Laid-Open No. 157847/85 proposes a technique belonging to the second category of producing a roll of a strip-shaped multilayer structure wound up on a drum by bonding a number of component strips, which is then dried and cut to sheets of unit size. This technique requires an apparatus having a complicated structure for aligning lines on the component strips in order to bond them together correctly and the adhesive agent used to bond the strips together requires to be dried well, making the technique as inefficient as the first one.
Each of the techniques belonging to the third type and disclosed in Japanese Patent Publication No. 30184/81 and Japanese Patent Laid-open No. 255422/85 entail complicated means for aligning sheets to be layered and cutting them to a unit length, making the overall process of manufacturing multilayer structures also rather complicated and cumbersome.
Any of the above described conventional methods and apparatuses thus comprise steps of drying the applied adhesive and cutting multilayered or single-layer strips to a unit length, requiring time from the application of adhesive agent to the formation of a multilayer structure and the operation of bonding component strips or sheets together and forming a multilayer structure cannot be carried out immediately after the application of adhesive agent.
Thus, if component strips or sheets for forming a honeycomb structure are composed of thin and soft or coarse tissues that are permeable to gas and water, any of the above quoted adhesive agents applied to a side of a strip can easily pass therethrough to the other side so that the bonded strips may become flat to form a single plate that may look like a plywood.
If a molten hot-melt type adhesive agent is applied to a side of a strip of a thin and soft or coarse material in an attempt to prevent it from passing to the other side, the long time spent from the application of the adhesive agent to the completion of the multilayering operation reduces the adhesiveness of the agent to consequently produce a honeycomb structure which is poor in stoutness. Additionally, the applied adhesive agent can easily pass to the other side to flatten the honeycomb structure once it is heated and/or put under pressure.
Furthermore, any of the above cited techniques involves cumbersome steps of detecting cutting positions on a strip, aligning the edges of prepared sheets and multilayering them neatly to a given number of layers, making it very difficult to manufacture high precision honeycomb structures.
When an adhesive agent is applied to each component sheet in a number of stripes and sheets are put together to form a multilayer structure, they can be swerved from one another to show a completely irregular arrangement as they are moved along a curved line from one work station to another.
In view of the above described problems and other problems of the prior art, it is therefore an object of the present invention to provide a method and an apparatus for manufacturing high quality laminate for honeycomb structure at a high yield by relatively simple means and without causing them to lose the honeycomb structure and become flat even if a thin and soft or coarse material which is permeable to gas and water and therefore through which an adhesive agent can easily pass is used.